Biological invasions have the potential to influence a suite of interacting ecosystem services by altering the structure and function of invaded communities. In this study we focus on the relationship between biodiversity as a supporting service and aesthetic experience as a cultural service in a woodland impacted by the invasive shrub European buckthorn (Ramnus cathartica) and the invasive forb garlic mustard (Alliaria petiolata). Different plant species assemblages in forest communities create differences in forest structure as a result of variation in plant size and architecture. Invasion by European buckthorn may increase shrub layer density and decrease light availability, thus impacting the diversity and abundance of ground layer vegetation. In turn, these changes in forest structure and composition may influence the aesthetic experience one has when visiting the forest by decreasing visibility distance, decreasing light, and altering the species composition. To address the hypothesis that invasion by European buckthorn and garlic mustard causes a decrease in forest enjoyment, we combined measurements of forest structure and composition with survey data collected from forest visitors in the Glenway Woods, a city park of Madison, WI, USA. We were also interested to explore whether or not variation in visitors’ ecological knowledge and their reported a priori preferences for certain forest attributes also influenced their aesthetic experiences. Data analysis used selection techniques to evaluate a family of models with the general form: forest structure & composition + a priori preferences + ecological knowledge = aesthetic experience.
Results suggest that forest structure and ecological knowledge were strong predictors of aesthetic experience, while forest composition and a priori preferences had little to no effect. In the Glenway Woods, degradation of the supporting service of biodiversity only appears to degrade the cultural service of aesthetic experience when the visitor has knowledge of invasive species. Otherwise, aesthetic experience is best predicted by forest structure alone, regardless of the species composition that creates this structure.